Variable cut-off  for steam-engines



UNITED STATES PATENT OFFICE.

A. CRUMBIE AND R. D. BRIGGS, OF BROOKLYN, NEW YORK.

VARIABLE CUT-OFFl FOR STEAM-ENGINES.

Specification of Letters Patent No. 28,830, dated May 3, 1859.

To all whom it 'may concern;

Be 1t known that we, ALEXANDER ORUMBIE `and RUSSELL D. BRIGcs, both ofthe city of Brooklyn, in the county of Kings and State of New York, haveinvented a new and Improved Variable Out-Off Gear for Steam- Engines;and we do hereby declare that the following is a full, clear, and exactdescription of the same, reference being had to the accompanyingdrawings, making part of this specification, in which- Figure 1 is aside view of our improved cut-off gear. Fig. 2 is a plan of one of therocking toes, sliding lifters, and tripping bars.

Similar letters of reference indicate like parts in both figures.

To enable those skilled in the art to make and use our invention, wewill proceed to describe its construction and op-eration.

A, A, represents either the stems of the cut-off valves or lifting rodsconnected with them. The valves may be either such as will serve alonefor the induction of steam or may be used with other induction valves.These rods are slotted transversely to receive the sliding lifters a,a', one each; the under sides of those portions of the said lifterswhich project from the rods or stems to lift the valves, being squarewith the rods or stems A, A, and the upper sides being beveled. Theseportions of the lifters project from those sides of the rods or stems A,A', which face each other, and springs Z), are applied on the oppositesides of said rods or stems to force out the. operative portions of thelifters, and said lifters are furnished with shoulders 3, 3, to preventthem being forced out by the springs farther than is necessary.Springs'cl, CZ', are shown as applied to the tops of the rods or stemsA, A, to force them down and close the valves but these may not be inall cases necessary.

C, C', are two rockers for operating on Y the lifters a, a, to lift thevalves, said rockers being of angular form and being arranged upon twostationary pins e, e', between the rods or stems A, A. The pendent armsof these rockers are connected together by a rod f, and are alsoconnected by a rod g, with an eccentric or its equivalent, for producingthe rocking motion necessary to lift the valves. Their toes la, 7L, haveraised feathers z', 2'-, on their working surfaces to enter grooves inthe points of the two togglelike tripping bars D, D', which areconnected by the same pin j, with an upright rod or slide E, which maybe connected with hand gear or with a governor, and whose joints areheld in contact with the working surfaces of the toes by means ofsprings 7c, 7s', in case of their own weight being insuflicient.

The operation is as follows: The vibratory motion of the rockers C, C,derived from the eccentric or its equivalent, causes the toes 7b, L, tooperate upon the lifters c, a, and raise the rods or stems A, A', andopen the valves till their respective tripping bars D, D, in beingraised by the toes and in gradually assuming a less inclined position,have their points moved toward the rods or stems so far that they pushback the sliding lifters a, a, through the rods or stems till they pushthem ofi' the toes and thus liberate the valves and allow them to close.The escape of the litters takes place earlier or later in the stroke ofthe piston according as the toggle-like tripping bars D, D, have a lessor more inclined position, and said tripping bars may be adjustedpermanently by lowering or raising the rod or slide E,to cause theescape of the lifters at an earlier or later point in every stroke ofthe piston, or they (the lifters) may be so controlled by a governorapplied to the rod E, as to make the cut-olf variable to regulate thespeed of the engine.

l/Ve do not claim any portion of the device patented by ll. T. Greene,March 13, 1855; but

Having described our invention, we claim and desire to secure by LettersPatent,

The arrangement and combination of the toggle-rods D, D, slide E,rockers C, C', stems Af, and lifters (a, a,) substantially as and forthe Apurpose herein shown and described.

ALEXANDER ORUMBIE. RUSSELL D. BRIGGS.

Witnesses:

WM. TUscI-I, S. H. WTALES.

